Expandable prefabricated building system and method of construction

ABSTRACT

An expandable prefabricated building system combines a preassembled rigid core unit with auxiliary floor sections and attached self-erecting or inflatable flexible membrane forms for satellite rooms surrounding the core unit. A preferred method of construction includes the steps of prefabricating a core unit and at least one floor section and flexible membrane form for a satellite room; transporting the prefabricated items to a construction site; erecting the core unit, floor section and flexible form; and applying hardenable plastic material to the flexible form to produce a permanent building.

United States Patent [1 1 Batorewicz et al.

[ Jan.1,1974

[ EXPANDABLE PREFABRICATED BUILDING SYSTEM AND METHOD OF CONSTRUCTION [75] Inventors: Valeria Batorewicz; Jerry P. Loving,

both of New Haven, Conn.

[73] Assignee: Housing Systems Corporation, New

Haven, Conn.

221 Filed: Aug. 31, 1971 211 Appl.No.: 176,636

[52] US. Cl 52/63, 52/l43, 52/236, 52/30), 52/74l I51 I Int. Cl E04b 1/12, E04h 1/347, E04b 1/35 [58] Field of Search 52/70, 71, 67, 63, 52/64, 143, 309, 236; 296/23, 23 A-23 G, 26, 27

[56] References Cited UNITED STATES PATENTS l,97l,977 8/1934 Erickson 52/63 Strope Fontaine 52/63 3,557,515 l/l97l MacCracken .l 52/2 FOREIGN PATENTS OR APPLICATIONS l,l96,077 6/1970 Great Britain 296/23 G Primary Examiner-John E. Murtagh Att0rneyCharles E. Hepner et al.

[57] ABSTRACT An expandable prefabricated building system combines a preassembled rigid core unit with auxiliary floor sections and attached self-erecting or inflatable flexible membrane forms for satellite rooms surrounding the core unit.

A preferred method of construction includes the steps of prefabricating a core unit and at least one floor section and flexible membrane form for a satellite room; transporting the prefabricated items to a construction site; erecting the core unit, floor section and flexible form; and applying hardenable plastic material to the flexible form to produce a permanent building.

12 Claims, 13 Drawing Figures PATENTED H974 v 3.782.063 sum 2 er a LIVING 64 BACKGROUND OF THE INVENTION This invention relates to building systems and methods of construction, particularly to housing systems adapted to be partially prefabricated and assembled prior to shipment to the erection site.

DESCRIPTION OF THE PRIOR ART A major consideration in the use of prefabrication techniques in building construction is to achieve the maximum cost saving from prefabrication and assembly under low cost, production-line, factory conditions without inordinately raising the shipping cost of the preassembled units to the installation site.

To a large extent, the prefabricated housing industry still uses conventional wood-frame construction in which factory operations are restricted to precutting the framing lumber, with most assembly operations performed at the building site. At the most, factory preassembly is limited to individual wall panels, roof trusses, and other subassemblies.

An exception to this pattern is the so-called mobile home industry which factory-produces a complete housing unit, even including furnishings. The dimensions of mobile home units are limited to the maximum size that can be trailed over the road, however, and each unit must be designed as a self-supporting structure capable of withstanding the stresses of over-theroad hauling. Furthermore, because of their special characteristics, mobile homes are subject to severe zoning restrictions.

In an extension of the mobile home concept, manufacturers have developed so-called modular housing, which consists of a number of prefabricated box-like units adapted for separate shipment to the building site where they are joined together to form a completed housing structure. Each unit is restricted in width and length to the dimensions permitted by highway regulations. The total volume of the units as shipped is equal to the total volume of the completed structure.

A separate development in building construction has been the use of inflated flexible membrane or fabric forms in conjunction with sprayed hardenable plastic material such as concrete or polyurethane foam for rapid erection of structures. Representative descriptions of prior art developments in these types of structures, as well as materials and techniques used in their construction, are given in US. Pat. Nos. 2,270,229 and 2,388,701 to W. Neff, No. 3,277,219 to L8. Turner, and No. 3,503,167 to W.L.Mackie.

These prior art developments in inflatable form construction are limited primarily to dome-shaped or semicylindrical structures, site-erected on a prepared foundation such as a concrete slab. As a possible variation, U.S. Pat. No. 3,277,219 to L8. Turner contemplates the use of an inflatable membrane as the form for the roof only of a building having walls of conventional masonry or frame construction. Whether encompassing an entire building or only the roof structure, these prior art uses of inflated form, foamed plastic construction have not contemplated factory preassembly because the high volume to weight ratio of the resulting structures makes shipment uneconomic.

SUMMARY OF THE INVENTION The present invention combines factory prefabrication of a high density core unit with rapid on-site erection of satellite rooms to create a unique housing system incorporating a maximum degree of factory prefabrication and preassembly with minimum shipping volume and featuring exceptional design flexibility.

The housing system of the invention comprises a preassembled box-like rigid core unit and a number of expandable satellite rooms surrounding the core. The core unit forms the central area of the completed housing structure. It preferably contains the primary service compartments such as kitchens and bathrooms, thus permitting the preinstallation of fixtures, plumbing and heating systems, and the major portion of the electric wiring for the complete structure.

In a preferred method of construction, prefabricated floor sections corresponding to the number of satellite rooms desired are attached at the factory around the periphery of the base of the core unit, preferably by hinges so they may be swung up vertically against the adjacent core unit walls to provide a compact package for shipment to the erection site. This method of packaging has the additional advantage of providing security against damage and pilferage during shipment and storage prior to erection at the building site. The over all size of the core unit with its floor sections folded up around the sides is necessarily restricted to the maximum dimensions permissible for the chosen method of shipment to the building site. Alternatively, the floor sections can be shipped as a separate package, thus permitting a slightly larger core unit, but with the disadvantage of increased labor at the erection site and loss of protection for the core unit during shipment and storage.

When the preassembled package arrives at the site, it can be set on a prepared foundation and the individual floor sections lowered and secured in place. Flexible membrane forms, preferably fitted to the edges of the floor sections at the factory and folded in as the floors are swung up into place for shipment, can then be stretched or inflated to assume the final shape of each of the satellite rooms surrounding the core box. Plastic material such as polyurethane foam is then applied to the inflated forms to create, when hardened, a permanent housing structure.

OBJECTS OF THE INVENTION An object of the invention is to provide a prefabricated housing system and method of construction incorporating a maximum degree of factory preassembly yet having low volume of the package as shipped compared with the volume of the completed structure as erected.

Another object is to provide a prefabricated housing system having a high degree of design flexibility.

Another object is to provide a housing system that makes optimum use of both traditional and new construction materials and techniques.

Other objects and advantages of the invention will appear from the following description of the preferred embodiment of the invention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of one embodiment of the invention as preassembled at the factory.

FIG. 2 is a perspective view of the embodiment of FIG. 1 packaged for shipment.

FIG. 3 is a plan section view of FIG. 2 along section lines 33.

FIG. 4 is an isometric view of the embodiment of FIG. 1 as erected at the building site.

FIG. 5 is a first floor plan of the completed housing structure of FIG. 4.

FIG. 6 is a second floor plan of the structure of FIG. 4.

FIG. 7 is an isometric view of a satellite room embodiment showing a preferred means of support for the flexible membrane form.

FIG. 8 is an elevation of the end wall of the satellite room of FIG. 7.

FIG. 9 is a partial detail in cross-section of a side elevation of a satellite room as completed.

FIG. 10 is a front elevation of an alternate embodiment of a house constructed according to the inventron.

FIG. 11 is a side elevation of the embodiment of FIG. 10.

FIG. 12 is a first floor plan of the embodiment of FIG. 10.

FIG. 13 is a second floor plan of the embodiment of FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the basic element of the present invention is a factory assembled box-like core unit 10. This unit is preferably of standard wood frame, gypsum board and plywood construction, but alternate construction may be used, for example: metal frame with plywood or gypsum infill panels, metal frame with plastic sandwich panels, or integral reinforced plastic sandwich panels. Surrounding one or more sides of core unit 10 are factory assembled floor sections l2, I3, 14 and 15. These floor sections provide bases for satellite rooms to be erected around core unit 10 at the building site and preferably are attached to the core unit by conventional metal hinges or continuous flexible tape hinges. If desired, wall panels, such as panels 16, 17, 18 and 19, can be hingedly attached to the outer edge of one or more of the floor sections. Their primary purpose is to provide support for flexible membrane forms for on-site application of hardenable plastic material to create the outer envelope of the satellite rooms, as will be described in detail below.

In a similar manner, wall panels, such as panels 20 and 22, can be hingedly attached to the top edges of one or more walls of core unit 10.

To obtain the maximum benefits of economy and quality control from factory preassembly, each core unit and its associated satellite room floor sections and wall panels can be completely finished and assembled before shipment. This includes finished floors (except in the vicinity of the hinged joints), walls, ceilings, doorways, and trim. While the assembled prefabricated structure is arranged in opened configuration, as in FIG. I, it is also desirable to permanently and smoothly fasten a flexible membrane form (such as forms 24 and 26 shown cutaway as examples) along the side edges of each floor panel and upright end wall panel, as well as to fasten it in the desired curve to the adjacent side wall of core unit 10; so that the forms assume the shape indicated in FIG. 1.

The advantage of factory preassembly of the flexible forms is that it is easier to tailor and adjust the forms for smooth, wrinkle-free fit there than under the conditions usually prevailing at the building site. Of course, if the floor sections for the satellite rooms are shipped separate from the core unit, the flexible forms must be attached at the building site.

The material used for the flexible membrane forms can be either woven or nonwoven, an impervious material such as sheet polyethylene or other plastic or a pervious fabric such as glass fiber or cotton cloth.

Glass fiber cloth or other fire retardant fabric is perferred for obvious safety reasons, but other form material can be used where local codes permit, particularly if it is subsequently covered with, for example, an intumescent-type paint such as is manufactured by Pratt- Lambert and having a flame rating of 10 on douglas fir. Treated paper or paper bonded to a plastic (e.g. polypropylene) sheet is also suitable for form material.

If no supporting structures such as the hinged end wall panels of FIG. 1 are used in the design, the membrane forms are preferably inflated to assume their intended shape. When inflatable forms are used, they should preferably be of light-weight, impervious material. On the other hand, end panels or supporting structures permit the use of pervious fabric, either stretched to be self-supporting, or draped over a net-like supporting means, as described below.

After preassembly has been completed, each hinged end wall panel is swung down against its corresponding floor section while the flexible form is carefully folded and arranged to prevent its tearing. Then the hinged floor sections are swung up against the sides of core unit 10 to make a compact package for shipment, as shown in FIG. 2.

Referring next to FIG. 3, the arrangement of the swung-up floor sections around the sides of core unit 10 can be clearly seen. FIG. 3 also illustrates the desirability of designing the housing structure so that the core unit contains all the service areas such as the kitchen 28, utility room 30 and bath 32. In this way, most of the necessary wiring and plumbing, as well as fixtures such as sink 34, stove unit 36, furnace 38, water heater 40, lavatory 42, toilet 44, and tub 46, can be installed at the factory. Also desirable is factory installation of kitchen and other built-in cabinets as well as other special joiner work such as stairway 48. In this way, the advantages of almost complete factory preassembly, as currently exemplified by the so-called mobile home, are combined with the capability of instant expansion at the erection site to a housing structure having several times the floor space possible with a mobile home. In addition to greater floor area, the expandable system of the present invention also has the potential, because of the design flexibility inherent in the use of the membrane forms, to provide higher ceilings and thereby a sense of spaciousness unobtainable with the building block type of prefabricated housing.

The floor plan of core unit 10, as shown in FIG. 3, is square, but it can clearly as well be rectangular, the only limitation being that the dimensions of the packaged assembly (or of the core unit if shipped alone) must be within the limits imposed by the intended mode of shipment, whether by truck, rail, or otherwise. It is also clear that the satellite floor panels need not extend the full length of each side, nor even along all sides; so that a great deal of design flexibility can be achieved within the basic concept of the invention.

When the prefabricated assembly arrives at the erection site, it can be set immediately on prepared foundation footings. Then the satellite floor sections are swung down and anchored to the foundation, and the hinged end walls are swung up and braced in upright positions. The membrane forms can then be attached, if this step was not done at the factory, and hardenable plastic material applied by spraying, troweling, or other known means to form the completed structure as shown in FIG. 4.

FIGS. 5 and 6 illustrate one possible arrangement of rooms and show the inherent flexibility of the system. For example, the stove unit 36 which was shown stored for shipment in hallway 50 in FIG. 3, is moved into the center of kitchen 28 to form an island counter after the building is erected on the site.

As described earlier, the flexible membrane forms can be stretched between the core unit and the end wall panels of the satellite rooms so as to be self-supporting. FIG. 7 illustrates a preferred supporting means, particularly for use with low strength form materials. This supporting means is simply a network 52 of cords or rope, preferably dacron or nylon. The network may comprise a single rope 54 threaded back and forth between core unit wall 56 and end wall' panel 16. The membrane form can then be simply draped over network 54 and fastened to wall 56 and 16.

FIG. 8 shows end panel 16 with a series of holes 58 spaced from the edge of the panel to receive rope 54. Holes 58 are spaced preferably about four inches apart and about the same distance from the panel edge. An additional series of wider spaced holes 60 are set as close as possible to the edge of the panel. A second rope 62 (see FIG. 9) threaded through holes 60 serves as a thickness gauge when applying the hardenable plastic material to the form.

Alternatively, or additionally, the forms can be supported by introducing air at a few inches of pressure into the structure by means ofa fan to increase their resistance to deformation under the load of sprayed-on plastic and also to smooth out any wrinkles resulting from folding during shipment or uneven stretching after erection.

When spraying the plastic material on the forms, it is preferable to put on only a light coating initially and then allow it to harden, particularly if no inflation pressure is used, so that the initial layer will itself serve to support additional layers until the desired thickness is built up.

The preferred plastic material for this application is a conventional resin and activator mixture producing a polyurethane foam which, when hardened, has a density of about 2 to 4 pounds per cubic foot. Special formulations of this material have been developed with approximately 5 to 6 percent flame inhibitors added to achieve low flame-spread and smoke ratings. Tests indicate that this material, when sprayed to a thickness of about three to five inches, possesses the necessary strength to serve as structural walls and roofs for houses and, in addition, has thermal insulating properties superior to any other building material. When a cord network is used to support the flexible form as described above, the network performs the important additional function of reinforcing the plastic structure, thus permitting reduced thickness.

Polyurethane foam is subject to deterioration by ultraviolet rays, however, and also has fairly low resilience and correspondingly low resistance to impact damage. Both of these drawbacks can be substantially remedied by applying a stucco-like mixture of resin and cement or sand to the exterior of the structure after it has been completely covered to the desired thickness with the polyurethane foam. A resin cement mixture suitable for this application is marketed under the trademark DRY-VIT. This exterior coating has the additional quality of being highly water repellant.

In FIG. 9 the construction of a typical satellite room of the invention is shown in cross-section. The built up roof structure comprises hardened plastic material 64, such as urethane foam applied to membrane form 66 which, in turn, is supported .by a cord network formed by rope 54. The foam is built up thick enough to cover gauge rope 62. A resin cement coating 68, as described above, covers both exterior and interior surfaces of the foam to provide impact strengthand water resistance.

FIGS. 10 through 13 are front and side elevations and first and second floor plans of a specific example of a housing structure according to the invention, proposed as a prototype low-cost housing unit in New Haven, Connecticut. The core unit of this example is rectangular instead of square, as in the embodiment of FIGS. 1 through 6. A comparison of the floor plans of FIGS. 12 and 13 with those of FIGS. 5 and 6 clearly illustrates the aforementioned design flexibility of the system.

The foregoing description of the presently preferred embodiments is to be considered as illustrative only. For example, the hardenable plastic material used to form the exterior walls of the housing structure is not limited to polyurethane foam or even to organic plastic material. Sprayed concrete, particularly lightweight cellular versions, could also be used, as well as combinations of foamed plastic and concrete layers in which an initial relatively thin polyurethane foam layer, for example, could be used to support a subsequent layer of the heavier concrete mixture.

Although the preferred method of applying the plastic material at the building site is by spraying onto the outside of the fabric forms, the invention also includes spraying the plastic on the inside or on both sides. For inside spraying, the workmen should be provided with masks and fresh air supplied through hoses from out- Side to protect them from the toxic fumes of the liquid plastic.

Other variations and embodiments will occur to those skilled in the art and are comprehended within the following claims.

We claim:

1. A prefabricated housing system for providing a preassembled package compact enough for shipment yet rapidly expandable to a full-size, multi-room permanent dwelling structure at an erection site, the system comprising:

a preassembled core service unit;

. at least one floor section for a satellite room pivotally attached to at least a portion of the lower edge of a corresponding side of the core unit at a level corresponding to the floor level in the core unit for swinging from a horizontal position to an upright 7 8 position adjacent to the side to make a compact the upper wall panels and the tops of the intervenpackage for shipment to an erection site; ing sides of the core unit, whereby the additional a flexible membrane form attached to each floor secmembrane form will be tensioned between the wall tion and to the corresponding side of the core unit; panels and the top of the core unit to assume the means for tensioning the membrane form attached to predetermined envelope shape of a second-story each floor section (0 assume apredeterrnined enveroom when the upper exterior wall panels are in lope shape of the satellite room when the correh i i l i i SPOIldil'lg flOOl' section is in its horizontal position 8 A permanent multiqoom housing tructure omfor receiving an applied layer of hardenable plastic i i material to create said permanent dwelling struc- 10 a prefabricated core service unit;

ture: at least one floor section for a corresponding satellite an additional flexible membrane form attached to the room, h fl ti atta h d t a sid of the top of the core unit; and re unit; means for tensioning the additional membrane form a fl ible membrane f attached to the sides of to assume predetel'mlnefi envelope Shape of a each floor section and the adjacent side of the core second-story room for receiving an applied layer of unit; hardenable plastic material to create a permanent means for tensioning the membrane f to assume second'stcfry rooma predetermined envelope shape of the corre- 2. The housing system of claim 1 wherein the means spending Satellite room. 1 1 s 7 for tenslorlmg the membrane form cflmpnses' an additional flexible membrane form attached to the an exterior wall panel for the satellite room pivotally top of the core unit.

attached to free edge of the floor panel spaced means for tensioning the additional membrane form from the one side of the core unit and adapted to to assume a predetermined envelope Shape of a be swung down from an upright position to a horiseeondetory room. and zontal position overlying the floor section, and the hardenable plastic material applied to the fuse flexible membrane form is attached along the mentioned flexible membrane form and to the adg g i the Ffi g f jg g the ditional flexible membrane form for providing rigid em m e mm M e enslone e ween e one envelope shapes for the corresponding satellite side of the core unit, the exterior panel, and the room and the second story room respectively Slqes of the floor section to assume the predeter' 9 The housing structure of claim 8 wherein the tenmmed fun headroom envelope shape of the Satel' sioriing means for the first-mentioned flexible memme r-oom when i floor Section the i panel brane form comprises at least one exterior wall panel are in their horizontal and vertical positions, respeedway. each panel being attached to one edge of one of the 3. The housing system of claim 2 and further comi g 5 2 52222 ss iz ggg g i sz giggz prising a network of flexible cord attached to the wall cor n p l g form is attached along the free edge of the exterior wall panel and the one wall of the core unit for supporting the membrane form in the predetermined envelope i whereby the first',memloned membrfme form tensroned between the side of the core unit, the extesha e when the floor section and wall anel are in their p p rlor wall panel, and the sides of the floor section to ashorizontal and vertical positions, respectively. 40

4. The housing System of claim 3, where the network sume a portion of the predetermined envelope shape of the corresponding satellite room.

of flexible cord comprises a rope threaded back and forth between the wall panel and the one wall of the Th housnlg Structure of dam 9 further comprising a tensioned network for supporting the flexcor unit.

5? housing System f Claim 1 wherein ible membrane form in the predetermined envelope the core unit comprises a polygonal structure, and Shape of the safehhe roomthe at least one floor section comprises a plurality of The housing Structure of Claim 9 wherein floor sections, a different floor section being atthe core comprises a polygonal Structure, and tached to each of a majority of the sides of the core the at least one floor Section comprises a plurality of unit. floor sections, a different floor section being at- 6. Th housing system f l i 5 h i h l tached to each of a majority of the sides of the core nal core unit is a rectangular structure and a different unitfloor section is attached to each side of the core unit. The housing Structure Of Claim 8 wherein the 7. The housing system of claim 1 wher i the means means for tensioning the additional flexible membrane for tensioning the second member comprises form comprises a pair of upper exterior wall panels ata pair of upper exterior wall panels hingedly attached tached at the tops of opposite sides of the core unit, the

at the tops of opposite sides of the core unit for additional membrane form being attached under tenswinging from an upright position to a horizontal sion to the free edges of the upper wall panels and the position overlying the core unit, the additional tops of the intervening sides of the core unit. membrane form being attached to the free edges of 

1. A prefabricated housing system for providing a preassembled package compact enough for shipment yet rapidly expandable to a full-size, multi-room permanent dwelling structure at an erection site, the system comprising: a preassembled core service unit; at least one floor section for a satellite room pivotally attached to at least a portion of the lower edge of a corresponding side of the core unit at a level corresponding to the floor level in the core unit for swinging from a horizontal position to an upright position adjacent to the side to make a compact package for shipment to an erection site; a flexible membrane form attached to each floor section and to the corresponding side of the core unit; means for tensioning the membrane form attached to each floor section to assume a predetermined envelope shape of the satellite room when the corresponding floor section is in its horizontal position for receiving an applied layer of hardenable plastic material to create said permanent dwelling structure: an additional flexible membrane form attached to the top of the core unit; and means for tensioning the additional membrane form to assume a predetermined envelope shape of a second-story room for receiving an applied layer of hardenable plastic material to create a permanent second-story room.
 2. The housing system of claim 1 wherein the means for tensioning the membrane form comprises: an exterior wall panel for the satellite room pivotally attached to one free edge of the floor panel spaced from the one side of the core unit and adapted to be swung down from an upright position to a horizontal position overlying the floor section, and the flexible membrane form is attached along the upper edge of the exterior wall panel, whereby the membrane form will be tensioned between the one side of the core unit, the exterior panel, and the sides of the floor section to assume the predetermined full headroom envelope shape of the satellite room when the floor section and the wall panel are in their horizontal and vertical positions, respectively.
 3. The housing system of claim 2 and further comprising a network of flexible cord attached to the wall panel and the one wall of the core unit for supporting the membrane form in the predetermined envelope shape when the floor section and wall panel are in their horizontal and vertical positions, respectively.
 4. The housing system of claim 3, where the network of flexible cord comprises a rope threaded back and forth between the wall panel and the one wall of the core unit.
 5. The housing system of claim 1 wherein the core unit comprises a polygonal structure, and the at least one floor section comprises a plurality of floor sections, a different floor section being attached to each of a majority of the sides of the core unit.
 6. The housing system of claim 5 wherein the polygonal core unit is a rectangular structure and a different floor section is attached to each side of the core unit.
 7. The housing system of claim 1 wherein the means for tensioning the second member comprises a pair of upper exterior wall panels hingedly attached at the tops of opposite sides of the core unit for swinging from an upright position to a horizontal position overlying the core unit, the additional membrane form being attached to the free edges of the upper wall panels and the tops of the intervening sides of the core unit, whereby the additional membrane form will be tensioned between the wall panels and the top of the core unit to assume the predetermined envelope shape of a second-story room when the upper exterior wall panels are in their vertical positions.
 8. A permanent multi-room housing structure comprising: a prefabricated core service unit; at least one floor section for a corresponding satellite room, each floor section attached to a side of the core unit; a flexible membrane form attached to the sides of each floor section and the adjacent side of the core unit; means for tensioning the membrane form to assume a predetermined envelope shape of the corresponding satellite room; an additional flexible membrane form attached to the top of the core unit; means for tensioning the additional membrane form to assume a predetermined envelope shape of a second-story room; and hardenable plastic material applied to the first-mentioned flexible membrane form and to the additional flexible membrane form for providing rigid envelope shapes for the corresponding satellite room and the second-story room, respectively.
 9. The housing structure of claim 8 wherein the tensioning means for the first-mentioned flexible membrane form comprises at least one exterior wall panel, each panel being attached to one edge of one of the floor sections opposite the corresponding side of the core unit, and the corresponding flexible membrane form is attached along the free edge of the exterior wall panel, whereby the first-mentioned membrane form is tensioned between the side of the core unit, the exterior wall panel, and the sides of the floor section to assume a portion of the predetermined envelope shape of the corresponding satellite room.
 10. The housing structure of claim 9 and further comprising a tensioned network for supporting the flexible membrane form in the predetermined envelope shape of the satellite room.
 11. The housing structure of claim 9 wherein the core unit comprises a polygonal structure, and the at least one floor section comprises a plurality of floor sections, a different floor section being attached to each of a majority of the sides of the core unit.
 12. The housing structure of claim 8 wherein the means for tensioning the additional flexible membrane form comprises a pair of upper exterior wall panels attached at the tops of opposite sides of the core unit, the additional membrane form being attached under tension to the free edges of the upper wall panels and the tops of the intervening sides of the core unit. 